MISS4X4

I have a 89 4.0L 6cyl (Renix of course) and today after I cleaned the IAC and the TB and put it all back together the idle was up high. It never idled high before I did this so I'm thinking there's a pretty direct connection. I'm afraid that carb cleaner may have been sprayed into the IAC, do you think that that would kill the IAC? I checked for vaccuum leaks but I recently replaced some of the vaccuum lines and can't find anything wrong with the other ones. I disconnected the vaccuum line to the MAP sensor and it idled fine but smells like it's running rich. I don't know if that has any affect on it whatsoever but thought it might help. Any ideas about why this is happening?

thorguy57

How long was it idling high for? Was it just burning off the cleaner? My first guess would have been a vacuum leaks but you said you already checked that so not sure. I would think the vacuum leak would be right around the IAC.

freegdr

try disconnecting the battery for about 10 minutes then try again maybe it will reset

freegdr

did the gasket to it get pinched or cut when you put it back in

MISS4X4

I drove it for at least 15 minutes and its been shut off and turned back on a bunch of times since. I checked again for vaccuum leaks but there isn't anything disconnected or loose or ripped.

MISS4X4

The IAC has a brand new Oring. Do you think maybe if someone sprayed the IAC directly with carb cleaner that might get into the motor and kill it?

mr-warwagon

if im not misstaken there is a tsb on the iac for that round about year , try to repace it the tip may be bad

freegdr

ive cleaned my plenty of times thru the years ive had it never had a problem card cleaner on it

798JMan

I cleaned one on my uncles 90xj. It had a high idle afterwards so I went and bought a new one. When I opened the box it had instruction on how to adjust it. You just take it off and either screw or unscrew a little.

xj4fun

Miss - I know this may sound like a broken record; I'm betting there is a vacumn leak somewhere in the system, even though you mentioned just replacing several hoses. I'm wondering if the remaining original hoses my have gotten cracked etc, while doing your IAC work.

While carb cleaner can damage some o2 sensors, I doubt the product could have a long term affect on idle.

Question; Is the high idle constant? By this I mean is it idling the same on a cold start up as it does when warmed up?

As an FYI IAC's shouldnt be adjusted! They are factory preset. With that said 'yes' early models do have a set screw (allen wrench) where you can override the factory preset. However I would only recommend that as a last resort. Yes this can work, but can cause the ECU to alter fuel mapping etc, as the idle signal is now outside the ECU's fuel mapping range.

Hope this helps
Kent

MISS4X4

XJ4FUN,

Thanks for your help! I've checked every damn hose on that thing and they are in great condition. I tried getting a new IAC from pickapart but that was a bad idea, I got 3 in varying condition. One made it idle so high I couldn't stand to let it suffer, I had to turn it off. The other two made the idle fluctuate, especially after it's had a chance to warm up a little. As my last resort I adjusted the pintle on the IAC and now it's running better. The idle isn't as high but it'll occassionally go up at a light or when I turn the off the engine it'll shoot up pretty high. It does smell like fuel more then it used to so I'm thinking that my IAC cleaner person turned the pintle and un adjusted it. Now it's adjusted a little closer to the proper setting but the fuel mapping is jacked up like you said. I may just have to give in and buy a new one to find out.

MISS4X4

Thanks! I think that really helped me identify my XJ's issue.

CenCaliAlum2010

I had this same issue after replacing the water pump and radiator on my 97 XJ 2.5L with somewhere over 250k miles (replaced dummy lighted gauge cluster with premium and now says 130k on the tach :P)

I spent over $100 to replace first the IAC and then TPS and cleaned the throttle body and idle bypass, but neither helped the idle. I then used carb cleaner and sprayed all possible vacuum hose leaks while the engine was running and noticed that spraying it next to the intake/exhaust manifold caused the engine to stutter.

Come to find out a $8 intake manifold gasket solved my issue... Add about 3hrs to do everything to remove the intake & exhaust manifolds, as well as complete a thorough intake manifold cleaning, replace the gasket and put everything back together. Now she purrs (at 800rpm's idling at all times) just like she's brand new again!

Removal of all the components to get the the manifold gasket took the most amount of time but it wasn't difficult for an average at-home mechanic with wal-mart tools haha. The shop wanted over $400 just in labor! so double check with the carb cleaner before doing any part replacements!